Spinal cord - lower extent

In adults, spinal cord extends to lower border of L1-L2 vertebrae. Subarachnoid space (which contains the CSF) extends to lower border of S2 vertebra. Lumbar puncture is usually performed between L3-L4 or L4-L5 (level of cauda equina)

Goal of lumbar puncture is to obtain sample of CSF without damaging spinal cord. To keep the cord "alive", keep the spinal needle between L3 and L5.

Exam will demonstrate absence of DTRs and (+) Romberg sign

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Syringomyelia

Syrinx expands and damages anterior white commissure of spinothalamic tract (2nd order neurons) - bilateral loss of pain and temp sensation (usually C8-T1); seen with Chiari I malformations; can expand and affect other tracts

Biceps = C5 nerve root

Triceps = C7 nerve root

Patella = L4 nerve root

Achilles = S1 nerve root

Reflexes count up in order:

S1,2 - "buckle my shoe" - Achilles

L3,4 - "kick the door" - Patellar

C5,6 - "pick up sticks" - biceps

C7,8 - "lay them straight" - triceps

L1,2 - "testicles move" - cremaster

S3,4 - "winks galore" - anal wink

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Primitive reflexes

CNS reflexes that are present in a healthy infant, but are absent in a neurologically intact adult

Normally disappear within 1st year of life. These primitive reflexes are inhibited by a mature/developing frontal lobe. They may remerge in adults following frontal lobe lesions - loss of inhibition of these reflexes

1) Moro reflex - "Hang on for life" reflex - abduct/extend arms when startled, and then draw together

2) Rooting reflex - Movement of head toward one side if cheek or mouth is stroked (nipple seeking)

3) Sucking reflex - Sucking response when roof of mouth is touched

4) Palmar reflex - curling of fingers if palm is stroked

5) Plantar reflex - Dorsiflexion of large toe and fanning of other toes with plantar stimulation

"Babinski" - presence of this reflex in an adult, which may signify UMN lesion

6) Galant reflex - Stroking along one side of the spine while newborn is in ventral suspension (face down) causes lateral flexion of lower body toward stimulated side

CN 4 damage

Eye moves upward, particularly with contralateral gaze and head tilt toward the side of the lesion (problems going down stairs, may present with compensatory head tilt in the opposite direction)

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CN 6 damage

Medially directed eye that cannot abduct

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Internuclear ophthalmoplegia

Medial longitudinal fasciculus (MLF): pair of tracts that allows for crosstalk between CN 6 and CN 3 nuclei. Coordinates both eyes to move in same horizontal direction. Highly myelinated (must communicate quickly so eyes move at same time). Lesions may be unilateral or bilateral (bilateral classically seen in MS)

When looking left, the left nucleus of CN 6 fires, which contracts the left lateral rectus and stimulates the contralateral (right) nucleus of CN 3 via the right MLF to contract the right medial rectus

Directional term (right INO, left INO) - refers to which eye is paralyzed

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Dementia - general

A decrease in cognitive ability, memory, or function with intact consciousness

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Alzheimer Disease

Most common cause of dementia in elderly. Down Syndrome patients have an increased risk of developing Alzheimer

Facial paralysis in 50% of cases. May see autonomic dysregulation (cardiac irregularities, HTN, hypotension) or sensory abnormalities. Almost all patients survive; the majority recover completely after weeks to months

Found in cerebral hemispheres. Can cross corpus callosum ("butterfly glioma")

Stain astrocytes for GFAP

Meningioma

Adult

Common, typically benign primary brain tumor. Most often occurs in convexities of hemispheres (near surfaces of brain) and parasagital region. Arises from arachnoid cells, is extra-axial (external to brain parenchyma), and may have a dural attachment ("tail").

Often asymptomatic; may present with seizures or focal neuro signs. Resection and/or radiosurgery